Linac4 status and perspectives Alessandra Lombardi and Maurizio Vretenar for the LINAC4 team Contents : Linac4 commissioning up to 160 MeV; Source; Debuncher; Reliability Run. LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

Made it to the final energy! Safely on the dump. It has been stripped. It has been delivered to the HST. Oct 2013 3MeV 30 mA Nov 2015 50 MeV 20 mA Nov 2016 160 MeV 18mA 45 KeV 50 mA LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

Layout and commissioning stages All items needed for the connection to the PSB are in house LINAC4 machine layout- 352MHz Pre-injector (9m) DTL (19m) CCDTL (25m) Π-mode (23m) 3MeV 50 MeV 100 MeV 160 MeV SOURCE Plasma Generator Extraction e-Dump LEBT 2 solenoids Pre chopper RFQ CHOPPER LINE 11 EMQ 3 Cavities 2 Chopper units In-line dump 3 Tanks 3 Klystrons : 5 MW 1 EMQ 114 PMQ 2 steerers 7 Modules 7 Klystrons : 7 MW 7 EMQ + 14 PMQ 7 steerers 12 Modules 8 Klystrons: 12MW 12 EMQ 12 steerer Beam Commissioning stages 45 keV 3 MeV 12 MeV 105 MeV Not yet the final source – details later (50mA standalone) (30mA-Nov15)***** 25mA – Nov16 October 2013 (10mA- Aug 14) (30mA-oct 15) (20mA-Nov15) 20 mA –Nov16 August 2014 (20mA – Nov15) November 2015 (20mA – Nov 15) 18mA –Nov2016 June 2016 (20mA – Jun16) October 2016 15mA – Nov 2016 LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

Beam CURRENT 160 Mev matching and steering 3 MeV 45 keV Source emittance RFQ acceptance LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

Beam Current BCT Energy intensity L4L.BCT.1213 45keV 25 mA Emittance/ 3 MeV 20 mA RFQ Acceptance L4L.BCT.4013 19mA L4C.BCT.0717 50 MeV 16mA Matching and L4T.BCT.0107 160 MeV 14 mA Steering LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

Reaching the final energy Characteristic curves : energy out of an RF cavity as function of amplitude and phase. Solid line : simulations, Dotted : measurements LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

Reaching the final energy LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

Transverse measurements From three (or more) profile measurements deduce the emittance. Technique refined in HSL by forward tracking and tomographic reconstruction. At 160 MeV X-X' Emit [rms] = 0.3188 Pi.mm.mrad [ Norm. ] Y-Y' Emit [rms] = 0.3295. ] LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

Main parameters LINAC4 – CDR (2006) LIU specs march 2015 LINAC4 – achieved (IN PROGRESS) Protons per bunch in 650 ns : 3 1012 in 1.5 µm 70mA peak at the source 65 ma peak in the linac 40 mA after chopping 60 mA peak at the source 40 mA peak in the linac 26 mA after chopping Injection over 20 turns 50mA peak 18 mA peak in the linac (30 mA potentially) 12 mA average after chopping (20 mA potentially) Injection over 40 turns (ok for LHC beams) 160 MeV 0.4 π mm mrad 0.3 π mm mrad (at 160 MeV) 400 µsec 1Hz Up to 600 µsec 1Hz Fast Chopping at 3 MeV 2µsec inj kicker rise-time Demonstrated , including transmitted beam quality LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

A word on the source Many improvement since march 2015 Intensity Stability Auto-Pilot (automatic regulation of critical source parameters for increased stability) Caesiation with autopilot , time needed went from half day w/o beam to few hours in degraded beam conditions Still needs attention Control of the emittance Optimised electrode shape Matching into the LEBT Mastering neutralisation? Current at 3 MeV before chopping Today’s LINAC4 20mA Record LINAC4 ( at 3 MeV) 30 mA Nominal LIU 40 mA Can be compensated with more injected turns in the PSB . Studies by Benedetto and Forte show that emittance is ok for LHC beams. LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

A word on the Debuncher PIMS-like cavity located approx. 40 m after the last PIMS with the purpose of adapting the energy spread to the desired value in the PSB (from 120keV to 700keV rms). Note that the energy spread from the linac is about 300keV. Without energy painting the needed voltage is 900kV. Ok. With energy painting, the debuncher has to adapt to the velocity profile along the macro-bunch, i.e. more power is needed from the amplifier to dynamically change the phase. With the current amplifier the de-buncher cannot adapt to any energy painting scheme and a compromise on speed/energy spread/range of energy painting is necessary https://indico.cern.ch/event/569203/ and https://indico.cern.ch/event/570568/ LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

Reliability Run Purpose : insure a smooth transition from commissioning to operation, achieve a beam-avaliability (tbd) for the PSB as high as possible and possibly above 90%. (https://indico.cern.ch/event/588169/) Phase When 0-Finalisation Before May 17 Consolidation of LLRF and BI instrumentation. CRUCIAL to respect the schedule 1-make the linac4 reliable by addressing weak points June - August Short runs followed by repairs/optimisation Accelerator Fault Tracker in place; OP involved with Linac team still leading. 2-Mock-up of operation as after the connection Sept- Mar18 (including 2 months shut-down) Daily preparation of different beams, continuous operation for weeks, exploitation of the LINAC4 flexibility) OP leading the run with linac team as support. Call-out list during working hours. LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

Reliability run – details Keep in place HST dump , to have the possibility to have multiple destinations/users and verify the energy. AFT + the expertise of the Aft team from the beginning (June 2017). Beam-on time calculated from the logbook entries keeping into account that there is not a piquet service. Software to facilitate running from the CCC should be transferred to OP or written by OP. needs have been identified. Main dump HST temporary dump LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

NEXT steps and planning Achieve the HST goals Achieve Reliability Run goals Intervention, repairs : alignment, vacuum DTL, source (and new LEBT?)….. LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

Summary and conclusions Construction and installation of LINAC4 finished at the end of 2016. A beam of 15mA at 160 MeV has been obtained at LINAC4, it has been stripped and delivered to the HST. The Nov 2016 measurement campaign confirms that all the technical choices for the linac are solid and that there are no fundamental show-stoppers or drastic changes needed. Further adjustments on the source and improvement of the matching/steering should allow to reach a minimal LIU LHC beam of 30mA (vs 40 nominal). The reliability run is the focus for 2017 and it is an important step in the transition to operation. LHC Performance Workshop 23-26 January 2017 Linac4 status and perspectives Alessandra Lombardi

LHC Performance Workshop 23-26 January 2017